How can one use solar energy after the sun sets? Simple: store the sun’s heat in molten salts.

The world’s first solar power plant to employ such technology—a thermal power plant that concentrates the sun’s rays with mirrors on long, thin tubes filled with the molten salt—opened in Syracuse, Sicily, on July 14. Dubbed Archimede—after the famous Syracusan scientist Archimedes who supposedly coined the term “Eureka” for scientific discovery and reputedly repelled a Roman fleet through the use of mirrors to concentrate the sun’s rays and burn the invading ships—the power plant can harvest enough heat to generate five megawatts of electricity, day or night, and can store enough energy to keep producing power even at night or during cloudy daytime hours.

In addition to the benefit of storage, molten salts also operate at a higher temperature (roughly 550 degrees Celsius) enabling them to capture more of the sun’s energy—as well as create the steam for turbines in conventional power plants. Meaning that such solar thermal power plants could be swapped in for fossil fuel-burning ones. This power plant is on the grounds of a natural gas combined-cycle power plant.